Polyurethane foam in foundation footings for load-bearing structures

Abstract

Foundation footing system for a load-bearing structure comprising a hole in the ground and a post in the hole extending above the hole. A gap present between the sides of the post and the sides of the hole contains a cured, hydrophobic, closed-cell, polyurethane foam to firmly hold the post in place and protect the post from moisture. Alternatively, a foundation footing system for a load-bearing structure comprising a hole in the ground filled with a cured, hydrophobic, closed-cell, polyurethane foam and a post place on and connected to the top of the foam.

We claim: 
     
       1. A foundation footing system comprising:
 a post configured to be positioned within a hole defined by a ground,
 the hole having a top, a bottom surface, a side surface extending therebetween, and a width wider than a width of the post such that the side surface of the hole defines a gap between a side surface of the post and the side surface of the hole, 
 the post having a length configured to extend from the bottom surface of the hole to beyond the top of the hole; and 
 
 a closed-cell polyurethane foam comprising a cured mixture of a polyurethane composition comprising polyisocyanate and at least one active hydrogen containing compound, 
 wherein the cured, closed-cell polyurethane foam is configured to fill the gap between the side surface of the post and the side surface of the hole, directly contact the ground, and provide an adhesive bond strength of at least 1200 pounds per foot embedded when the post has a cross-sectional perimeter of eight inches. 
 
     
     
       2. The foundation footing system of  claim 1 , wherein the cured, closed-cell polyurethane foam provides an adhesive bond strength of least 1300 pounds when tested by embedding one foot of a post having a cross-sectional perimeter of eight inches within the polyurethane composition, allowing the polyurethane composition to cure, pressing the post through the cured, closed-cell polyurethane foam, and measuring the adhesive bond strength with a compression-tension tester. 
     
     
       3. The foundation footing system of  claim 1 , wherein the cured, closed-cell polyurethane foam provides an adhesive bond strength of least 1600 pounds when tested by embedding one foot of a post having a cross-sectional perimeter of eight inches within the polyurethane composition, allowing the polyurethane composition to cure, pressing the post through the cured, closed-cell polyurethane foam, and measuring the adhesive bond strength with a compression-tension tester. 
     
     
       4. The foundation footing system of  claim 1 , wherein the cured, closed-cell polyurethane foam has a density no greater than 0.075 g/mL. 
     
     
       5. The foundation footing system of  claim 1 , wherein the cured, closed-cell polyurethane foam has a density no greater than 0.05 g/mL. 
     
     
       6. The foundation footing system of  claim 1 , wherein the polyurethane composition foam is configured to be cured to touch in about 3 to 20 minutes after combining the polyisocyanate and the at least one active hydrogen containing compound. 
     
     
       7. The foundation footing system of  claim 1 , wherein the cured, closed-cell polyurethane foam has a compressive strength of from about 40 psi to about 100 psi. 
     
     
       8. The foundation footing system of  claim 1 , wherein the cured, closed-cell polyurethane foam is hydrophobic. 
     
     
       9. A foundation footing system comprising:
 a post configured to be placed within a hole defined within a ground,
 the hole having a top defined by the surface of the ground, a bottom surface, a side surface extending therebetween, and a width wider than a width of the post such that the side surface of the hole defines a gap between a side surface of the post and the side surface of the hole, 
 the post having a length configured to extend from the bottom surface of the hole to beyond the top of the hole; and 
 
 a closed-cell polyurethane foam comprising a cured mixture of a polyurethane composition comprising polyisocyanate and at least one active hydrogen containing compound, 
 wherein the cured, closed-cell polyurethane foam is configured to fill the gap between the side surface of the post and the side surface of the hole and directly contact the ground, and 
 the cured, closed-cell polyurethane foam provides an adhesive bond strength of least 1200 pounds when tested by embedding one foot of a post having a cross-sectional perimeter of eight inches within the polyurethane composition, allowing the polyurethane composition to cure, pressing the post through the cured, closed-cell polyurethane foam, and measuring the adhesive bond strength with a compression-tension tester. 
 
     
     
       10. The foundation footing system of  claim 9 , wherein the cured, closed-cell polyurethane foam provides an adhesive bond strength of least 1300 pounds when tested by embedding one foot of a post having a cross-sectional perimeter of eight inches within the polyurethane composition, allowing the polyurethane composition to cure, pressing the post through the cured, closed-cell polyurethane foam, and measuring the adhesive bond strength with a compression-tension tester. 
     
     
       11. The foundation footing system of  claim 9 , wherein the cured, closed-cell polyurethane foam provides an adhesive bond strength of least 1600 pounds when tested by embedding one foot of a post having a cross-sectional perimeter of eight inches within the polyurethane composition, allowing the polyurethane composition to cure, pressing the post through the cured, closed-cell polyurethane foam, and measuring the adhesive bond strength with a compression-tension tester. 
     
     
       12. The foundation footing system of  claim 9 , wherein the cured, closed-cell polyurethane foam has a density no greater than 0.075 g/mL. 
     
     
       13. The foundation footing system of  claim 9 , wherein the cured, closed-cell polyurethane foam has a density no greater than 0.05 g/mL. 
     
     
       14. The foundation footing system of  claim 9 , wherein the polyurethane composition foam is configured to be cured to touch in about 3 to 20 minutes after combining the polyisocyanate and at the least one active hydrogen containing compound. 
     
     
       15. The foundation footing system of  claim 9 , wherein the cured, closed-cell polyurethane foam has a compressive strength of from about 40 psi to about 100 psi. 
     
     
       16. The foundation footing system of  claim 9 , wherein the cured, closed-cell polyurethane foam is hydrophobic.